Diagnosis
The fill tube from the water valve to the icemaker is frozen solid. This is the most common failure mode for this model.
How to Fix It
Manually defrost the fill tube. Unplug the refrigerator. Remove the icemaker assembly (two Torx T15 screws). Locate the plastic fill tube directly behind it. Use a hair dryer on low heat to thaw the tube for 2-3 minutes. Reinstall the icemaker and plug the unit back in.
If That Didn't Work
The water inlet valve itself may be faulty. Check for water flow. Disconnect the refrigerator's water supply line at the valve and direct it into a bucket. Trigger a water dispenser cycle. If no water flows, the valve or household supply is the issue.
Heads Up
After thawing, run several ice maker cycles. The first few batches may be small or misshapen as the system stabilizes. Discard them.